The present invention relates to a frame for a motor vehicle door having a panel connected to the frame, the frame including two uprights, a front upright and a rear upright respectively, connected to the panel at their lower ends and joined at their upper ends by a cross member, and being adapted to define, together with the upper edge of the panel, a space for the window associated with the door.
Known frames of the type indicated above may be formed by a first box section which constitutes one of the two uprights and a second box section which constitutes the cross member and the other upright and is welded to one end of the first section, or by a single section which constitutes the cross member and the two uprights. In both cases, the sections are bent so as to assume the desired shape. They necessarily have a constant cross-section but, from the structural point of view, it would be desirable for the uprights to have larger cross-sections at their lower ends which are more stressed mechanically.
Moreover, motor vehicle doors are known which are constituted by two half-shells, each formed by a lower panel with an integral frame, produced by pressing and subsequently combined. The desired variation of the dimensions of the frame can thus be achieved by the suitable shaping of the two half-shells. However, it is necessary to use a pressing technique much more complex and expensive than that described above.